The main objective of this project is to develop a Virtual Reality (VR) System to be used for testing patients with neurological disorders and normal volunteers in the cognitive neuropsychology laboratory as well as in the functional neuroimaging environment (using functional magnetic resonance imaging r positron emission tomography). Specifically each of three VR systems ordered will include A) head-mounted displays for behavioral testing (non-MRI); B) a scanner mounted display for MR or PET for early pilot work; D) 1024x768 hood mounted display with LCD shutter stereo displays for PET and MRI; E) virtual reality software for moving through multiple environments based on the Alice virtual world environment and a separate 3-D object library for studies of grasp, touch and praxis; F) simple contact finger glove and 18 joint sensing glove; G) tactile feedback using vibration transducers; H) integration with PET IFIS experimental control systems (which include experimental control over auditory and visual tasks); and I) movement sensing in the MR and PET scanner to track head movement during runs. The VR System will be used to test patients who have unusual movement of visual disorders that precludes normal testing procedures, to immerse subjects in a 3- D environment, and to develop simulated virtual environments that will allow us to mimic and compress subject performance in real-life activities to a manageable time frame.